The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Receive-side scaling (RSS) is a network interface card (NIC) technology that involves routing data packets to different processor cores of an application processor. In RSS, the NIC may send different received packets to different receive queues to distribute processing among processor cores. The NIC distributes packets by applying a filter to each packet, where the filter assigns each packet to a logical flow of a number of logical flows. Packets for each logical flow are sent to a separate receive queue associated with a processor core, where each processor core obtains packets to process from their corresponding receive queue.
The existing RSS filter is a hash of network and/or transport layer headers, for example, a 4-tuple hash over IP addresses and TCP ports of a packet. This involves calculating a hash using the values of IP and TCP header fields of each IP packet including a source address, destination address, source port, and destination port to obtain a key. The key is used for a hash table lookup operation to find a processor core identifier (ID) or a receive queue number. For example, where a 128-entry indirection table is used, the receive queue for a packet may be determined by masking out the low order seven bits of the computed hash for a packet, using this number as the key into the indirection table, and reading the corresponding value from the table. Once the processor core ID/receive queue number is obtained, the data packet is sent to the processor core associated with the processor core ID. Performing the hash operation for each IP packet requires a relatively large amount of computational resources. Given the limited processing power of baseband processors of Fourth Generation (4G)/Fifth Generation (5G) modems, such costly hash operations performed for each IP packet may degrade downlink (DL) throughput.